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API</a><!----></li><li class="sidebar-link"><a class="sidebar-link-item" href="transitions.html">Transitions</a><!----></li><li class="sidebar-link"><a class="sidebar-link-item" href="scroll-behavior.html">Scroll Behavior</a><!----></li><li class="sidebar-link"><a class="sidebar-link-item" href="lazy-loading.html">Lazy Loading Routes</a><!----></li><li class="sidebar-link"><a class="sidebar-link-item" href="extending-router-link.html">Extending RouterLink</a><!----></li><li class="sidebar-link"><a class="sidebar-link-item" href="navigation-failures.html">Navigation Failures</a><!----></li><li class="sidebar-link"><a class="sidebar-link-item" href="dynamic-routing.html">Dynamic Routing</a><!----></li></ul></li><li class="sidebar-link"><a class="sidebar-link-item" href="index18.html">Migrating from Vue 2</a><!----></li><!--]--></ul><!--[--><!--[--><div class="sponsors" data-v-46b24580=""><span data-v-46b24580="">Sponsors</span><!--[--><a href="javascript:;" target="_blank" rel="noopener" data-v-46b24580=""><img src="https://posva-sponsors.pages.dev/logos/vuejobs.svg" alt="VueJobs" data-v-46b24580=""></a><!--]--></div><!--]--><!--]--></aside><div class="sidebar-mask"></div><main class="page" data-v-7eddb2c4=""><div class="container" data-v-7eddb2c4=""><!--[--><!--[--><div id="ads-container"><div class="carbon-ads" ref_key="el" data-v-5941b830=""></div></div><!--]--><!--[--><!--]--><!--]--><div style="position:relative;" class="content" data-v-7eddb2c4=""><div><h1 id="data-fetching" tabindex="-1">Data Fetching <a class="header-anchor" href="#data-fetching" aria-hidden="true">#</a></h1><p>Sometimes you need to fetch data from the server when a route is activated. For example, before rendering a user profile, you need to fetch the user&#39;s data from the server. We can achieve this in two different ways:</p><ul><li><p><strong>Fetching After Navigation</strong>: perform the navigation first, and fetch data in the incoming component&#39;s lifecycle hook. Display a loading state while data is being fetched.</p></li><li><p><strong>Fetching Before Navigation</strong>: Fetch data before navigation in the route enter guard, and perform the navigation after data has been fetched.</p></li></ul><p>Technically, both are valid choices - it ultimately depends on the user experience you are aiming for.</p><h2 id="fetching-after-navigation" tabindex="-1">Fetching After Navigation <a class="header-anchor" href="#fetching-after-navigation" aria-hidden="true">#</a></h2><p>When using this approach, we navigate and render the incoming component immediately, and fetch data in the component&#39;s <code>created</code> hook. It gives us the opportunity to display a loading state while the data is being fetched over the network, and we can also handle loading differently for each view.</p><p>Let&#39;s assume we have a <code>Post</code> component that needs to fetch the data for a post based on <code>$route.params.id</code>:</p><div class="language-html"><pre><code><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>template</span><span class="token punctuation">&gt;</span></span>
  <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>div</span> <span class="token attr-name">class</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">&quot;</span>post<span class="token punctuation">&quot;</span></span><span class="token punctuation">&gt;</span></span>
    <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>div</span> <span class="token attr-name">v-if</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">&quot;</span>loading<span class="token punctuation">&quot;</span></span> <span class="token attr-name">class</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">&quot;</span>loading<span class="token punctuation">&quot;</span></span><span class="token punctuation">&gt;</span></span>Loading...<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>div</span><span class="token punctuation">&gt;</span></span>

    <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>div</span> <span class="token attr-name">v-if</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">&quot;</span>error<span class="token punctuation">&quot;</span></span> <span class="token attr-name">class</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">&quot;</span>error<span class="token punctuation">&quot;</span></span><span class="token punctuation">&gt;</span></span>{{ error }}<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>div</span><span class="token punctuation">&gt;</span></span>

    <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>div</span> <span class="token attr-name">v-if</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">&quot;</span>post<span class="token punctuation">&quot;</span></span> <span class="token attr-name">class</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">&quot;</span>content<span class="token punctuation">&quot;</span></span><span class="token punctuation">&gt;</span></span>
      <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>h2</span><span class="token punctuation">&gt;</span></span>{{ post.title }}<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>h2</span><span class="token punctuation">&gt;</span></span>
      <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>p</span><span class="token punctuation">&gt;</span></span>{{ post.body }}<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>p</span><span class="token punctuation">&gt;</span></span>
    <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>div</span><span class="token punctuation">&gt;</span></span>
  <span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>div</span><span class="token punctuation">&gt;</span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>template</span><span class="token punctuation">&gt;</span></span>
</code></pre></div><div class="language-js"><pre><code><span class="token keyword">export</span> <span class="token keyword">default</span> <span class="token punctuation">{</span>
  <span class="token function">data</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">return</span> <span class="token punctuation">{</span>
      <span class="token literal-property property">loading</span><span class="token operator">:</span> <span class="token boolean">false</span><span class="token punctuation">,</span>
      <span class="token literal-property property">post</span><span class="token operator">:</span> <span class="token keyword">null</span><span class="token punctuation">,</span>
      <span class="token literal-property property">error</span><span class="token operator">:</span> <span class="token keyword">null</span><span class="token punctuation">,</span>
    <span class="token punctuation">}</span>
  <span class="token punctuation">}</span><span class="token punctuation">,</span>
  <span class="token function">created</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token comment">// watch the params of the route to fetch the data again</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">$watch</span><span class="token punctuation">(</span>
      <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token keyword">this</span><span class="token punctuation">.</span>$route<span class="token punctuation">.</span>params<span class="token punctuation">,</span>
      <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
        <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">fetchData</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
      <span class="token punctuation">}</span><span class="token punctuation">,</span>
      <span class="token comment">// fetch the data when the view is created and the data is</span>
      <span class="token comment">// already being observed</span>
      <span class="token punctuation">{</span> <span class="token literal-property property">immediate</span><span class="token operator">:</span> <span class="token boolean">true</span> <span class="token punctuation">}</span>
    <span class="token punctuation">)</span>
  <span class="token punctuation">}</span><span class="token punctuation">,</span>
  <span class="token literal-property property">methods</span><span class="token operator">:</span> <span class="token punctuation">{</span>
    <span class="token function">fetchData</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
      <span class="token keyword">this</span><span class="token punctuation">.</span>error <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>post <span class="token operator">=</span> <span class="token keyword">null</span>
      <span class="token keyword">this</span><span class="token punctuation">.</span>loading <span class="token operator">=</span> <span class="token boolean">true</span>
      <span class="token comment">// replace `getPost` with your data fetching util / API wrapper</span>
      <span class="token function">getPost</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">.</span>$route<span class="token punctuation">.</span>params<span class="token punctuation">.</span>id<span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token parameter">err<span class="token punctuation">,</span> post</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
        <span class="token keyword">this</span><span class="token punctuation">.</span>loading <span class="token operator">=</span> <span class="token boolean">false</span>
        <span class="token keyword">if</span> <span class="token punctuation">(</span>err<span class="token punctuation">)</span> <span class="token punctuation">{</span>
          <span class="token keyword">this</span><span class="token punctuation">.</span>error <span class="token operator">=</span> err<span class="token punctuation">.</span><span class="token function">toString</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
        <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
          <span class="token keyword">this</span><span class="token punctuation">.</span>post <span class="token operator">=</span> post
        <span class="token punctuation">}</span>
      <span class="token punctuation">}</span><span class="token punctuation">)</span>
    <span class="token punctuation">}</span><span class="token punctuation">,</span>
  <span class="token punctuation">}</span><span class="token punctuation">,</span>
<span class="token punctuation">}</span>
</code></pre></div><h2 id="fetching-before-navigation" tabindex="-1">Fetching Before Navigation <a class="header-anchor" href="#fetching-before-navigation" aria-hidden="true">#</a></h2><p>With this approach we fetch the data before actually navigating to the new route. We can perform the data fetching in the <code>beforeRouteEnter</code> guard in the incoming component, and only call <code>next</code> when the fetch is complete:</p><div class="language-js"><pre><code><span class="token keyword">export</span> <span class="token keyword">default</span> <span class="token punctuation">{</span>
  <span class="token function">data</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">return</span> <span class="token punctuation">{</span>
      <span class="token literal-property property">post</span><span class="token operator">:</span> <span class="token keyword">null</span><span class="token punctuation">,</span>
      <span class="token literal-property property">error</span><span class="token operator">:</span> <span class="token keyword">null</span><span class="token punctuation">,</span>
    <span class="token punctuation">}</span>
  <span class="token punctuation">}</span><span class="token punctuation">,</span>
  <span class="token function">beforeRouteEnter</span><span class="token punctuation">(</span><span class="token parameter">to<span class="token punctuation">,</span> from<span class="token punctuation">,</span> next</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token function">getPost</span><span class="token punctuation">(</span>to<span class="token punctuation">.</span>params<span class="token punctuation">.</span>id<span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token parameter">err<span class="token punctuation">,</span> post</span><span class="token punctuation">)</span> <span class="token operator">=&gt;</span> <span class="token punctuation">{</span>
      <span class="token function">next</span><span class="token punctuation">(</span><span class="token parameter">vm</span> <span class="token operator">=&gt;</span> vm<span class="token punctuation">.</span><span class="token function">setData</span><span class="token punctuation">(</span>err<span class="token punctuation">,</span> post<span class="token punctuation">)</span><span class="token punctuation">)</span>
    <span class="token punctuation">}</span><span class="token punctuation">)</span>
  <span class="token punctuation">}</span><span class="token punctuation">,</span>
  <span class="token comment">// when route changes and this component is already rendered,</span>
  <span class="token comment">// the logic will be slightly different.</span>
  <span class="token keyword">async</span> <span class="token function">beforeRouteUpdate</span><span class="token punctuation">(</span><span class="token parameter">to<span class="token punctuation">,</span> <span class="token keyword">from</span></span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token keyword">this</span><span class="token punctuation">.</span>post <span class="token operator">=</span> <span class="token keyword">null</span>
    <span class="token keyword">try</span> <span class="token punctuation">{</span>
      <span class="token keyword">this</span><span class="token punctuation">.</span>post <span class="token operator">=</span> <span class="token keyword">await</span> <span class="token function">getPost</span><span class="token punctuation">(</span>to<span class="token punctuation">.</span>params<span class="token punctuation">.</span>id<span class="token punctuation">)</span>
    <span class="token punctuation">}</span> <span class="token keyword">catch</span> <span class="token punctuation">(</span>error<span class="token punctuation">)</span> <span class="token punctuation">{</span>
      <span class="token keyword">this</span><span class="token punctuation">.</span>error <span class="token operator">=</span> error<span class="token punctuation">.</span><span class="token function">toString</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token punctuation">}</span>
  <span class="token punctuation">}</span><span class="token punctuation">,</span>
<span class="token punctuation">}</span>
</code></pre></div><p>The user will stay on the previous view while the resource is being fetched for the incoming view. It is therefore recommended to display a progress bar or some kind of indicator while the data is being fetched. If the data fetch fails, it&#39;s also necessary to display some kind of global warning message.</p></div></div><footer class="page-footer" data-v-7eddb2c4="" data-v-fb8d84c6=""><div class="edit" data-v-fb8d84c6=""><div class="edit-link" data-v-fb8d84c6="" data-v-1ed99556=""><a class="link" href="javascript:;" target="_blank" rel="noopener noreferrer" data-v-1ed99556="">Suggest changes to this page <svg class="icon outbound icon" xmlns="http://www.w3.org/2000/svg" aria-hidden="true" x="0px" y="0px" viewbox="0 0 100 100" width="15" height="15" data-v-1ed99556=""><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path><polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg></a></div></div><div class="updated" data-v-fb8d84c6=""><!----></div></footer><div class="next-and-prev-link" data-v-7eddb2c4="" data-v-38ede35f=""><div class="container" data-v-38ede35f=""><div class="prev" data-v-38ede35f=""><a class="link" href="javascript:;" data-v-38ede35f=""><svg xmlns="http://www.w3.org/2000/svg" viewbox="0 0 24 24" class="icon icon-prev" data-v-38ede35f=""><path d="M19,11H7.4l5.3-5.3c0.4-0.4,0.4-1,0-1.4s-1-0.4-1.4,0l-7,7c-0.1,0.1-0.2,0.2-0.2,0.3c-0.1,0.2-0.1,0.5,0,0.8c0.1,0.1,0.1,0.2,0.2,0.3l7,7c0.2,0.2,0.5,0.3,0.7,0.3s0.5-0.1,0.7-0.3c0.4-0.4,0.4-1,0-1.4L7.4,13H19c0.6,0,1-0.4,1-1S19.6,11,19,11z"></path></svg><span class="text" data-v-38ede35f="">Route Meta Fields</span></a></div><div class="next" data-v-38ede35f=""><a class="link" href="javascript:;" data-v-38ede35f=""><span class="text" data-v-38ede35f="">Composition API</span><svg xmlns="http://www.w3.org/2000/svg" viewbox="0 0 24 24" class="icon icon-next" data-v-38ede35f=""><path d="M19.9,12.4c0.1-0.2,0.1-0.5,0-0.8c-0.1-0.1-0.1-0.2-0.2-0.3l-7-7c-0.4-0.4-1-0.4-1.4,0s-0.4,1,0,1.4l5.3,5.3H5c-0.6,0-1,0.4-1,1s0.4,1,1,1h11.6l-5.3,5.3c-0.4,0.4-0.4,1,0,1.4c0.2,0.2,0.5,0.3,0.7,0.3s0.5-0.1,0.7-0.3l7-7C19.8,12.6,19.9,12.5,19.9,12.4z"></path></svg></a></div></div></div><!--[--><!--[--><!--]--><!--[--><div class="buy-sell-ads" data-v-4ce5ad17=""><div class="bsa-cpc" data-v-4ce5ad17=""></div></div><!--]--><!--]--></div></main></div><!----><!--]--></div></div>
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